IBM DB2 Manual page 265

You should set the trace properties under the direction of IBM Software
Support.
db2.jcc.traceLevel or db2.jcc.override.traceLevel
Specifies what to trace.
The db2.jcc.override.traceLevel property overrides the traceLevel property for
a Connection or DataSource object.
You specify one or more trace levels by specifying a decimal value. The trace
levels are the same as the trace levels that are defined for the traceLevel
property on a Connection or DataSource object.
To specify more than one trace level, do an OR (|) operation on the values,
and specify the result in decimal in the db2.jcc.traceLevel or
db2.jcc.override.traceLevel specification.
For example, suppose that you want to specify TRACE_DRDA_FLOWS and
TRACE_CONNECTIONS for db2.jcc.override.traceLevel.
TRACE_DRDA_FLOWS has a hexadecimal value of X'40'.
TRACE_CONNECTION_CALLS has a hexadecimal value of X'01'. To specify
both traces, do a bitwise OR operation on the two values, which results in
X'41'. The decimal equivalent is 65, so you specify:
db2.jcc.override.traceLevel=65
db2.jcc.ssid
Specifies the DB2 for z/OS subsystem to which applications make connections
with IBM Data Server Driver for JDBC and SQLJ type 2 connectivity on DB2
for z/OS.
The db2.jcc.ssid value can be the name of the local DB2 subsystem or a group
attachment name.
For example:
db2.jcc.ssid=DB2A
The ssid Connection and DataSource property overrides db2.jcc.ssid.
If you specify a group attachment name, and the DB2 subsystem to which an
application is connected fails, the connection terminates. However, when new
connections use that group attachment name, DB2 for z/OS uses group
attachment processing to find an active DB2 subsystem to which to connect.
If you do not specify the db2.jcc.ssid property, the IBM Data Server Driver for
JDBC and SQLJ uses the SSID value from the DSNHDECP data-only load
module. When you install DB2 for z/OS, a DSNHDECP module is created in
the prefix.SDSNEXIT data set and the prefix.SDSNLOAD data set. Other
DSNHDECP load modules might be created in other data sets for selected
applications.
The IBM Data Server Driver for JDBC and SQLJ must load a DSNHDECP
module before it can read the SSID value. z/OS searches data sets in the
following places, and in the following order, for the DSNHDECP module:
1. Job pack area (JPA)
2. TASKLIB
3. STEPLIB or JOBLIB
4. LPA
5. Libraries in the link list
You need to ensure that if your system has more than one copy of the
DSNHDECP module, z/OS finds the data set that contains the correct copy for
the IBM Data Server Driver for JDBC and SQLJ first.
Chapter 7. JDBC and SQLJ reference information
249